Friction and wear behavior of ultra-high molecular weight polyethylene (UHMWPE) sliding against AISI420C austenitic stainless steel and against TiAl6V4 alloy under dry and lubricated conditions were investigated with a reciprocating pin-on-flat tribometer for comparative purposes. The tests were conducted by varying frequency of the pin alternative motion and the applied normal load. For the tests in lubricated conditions a fluid containing a large amount of sodium hyaluronate has been chosen. By using an electronic precision balance the wear mass loss of the UHMWPE samples was evaluated accordingly. Friction is greatly reduced by the presence of UHMWPE and this is believed to be due to the formation of a lubricating film of UHMWPE in the contact zone. Furthermore, the experimental investigation shows that the AISI420C/UHMWPE gives, in dry conditions, better values in the wear rate and in the friction coefficient than the TiAl6V4/UHMWPE.